A reforming element for a molten carbonate fuel cell stack and corresponding methods are provided that can reduce or minimize temperature differences within the fuel cell stack when operating the fuel cell stack with enhanced CO.sub.2 utilization. The reforming element can include at least one surface with a reforming catalyst deposited on the surface. A difference between the minimum and maximum reforming catalyst density and/or activity on a first portion of the at least one surface can be 20% to 75%, with the highest catalyst densities and/or activities being in proximity to the side of the fuel cell stack corresponding to at least one of the anode inlet and the cathode inlet.

A fuel cell system includes a fuel feeder that supplies fuel, a fuel cell stack that generates power through an electrochemical reaction using air and a hydrogen-containing gas generated from the fuel, a first temperature sensor that senses the temperature of the fuel cell stack, and a controller. The fuel cell stack has a membrane electrode assembly including an electrolyte membrane through which protons can pass, a cathode on one side of the electrolyte membrane, and an anode on the other side of the electrolyte membrane. The controller defines an upper limit of current output from the fuel cell stack on the basis of the temperature of the fuel cell stack, the supply of the fuel, and the hydrogen consumption of the fuel cell stack associated with internal leakage current and keeps the current output from the fuel cell stack at or below the upper limit.

Disclosed here is a supported catalyst comprising a thermally stable core, wherein the thermally stable core comprises a metal oxide support and nickel disposed in the metal oxide support, wherein the metal oxide support comprises at least one base metal oxide and at least one transition metal oxide or rare earth metal oxide mixed with or dispersed in the base metal oxide. Optionally the supported catalyst can further comprise an electrolyte removing layer coating the thermally stable core and/or an electrolyte repelling layer coating the electrolyte removing layer, wherein the electrolyte removing layer comprises at least one metal oxide, and wherein the electrolyte repelling layer comprises at least one of graphite, metal carbide and metal nitride. Also disclosed is a molten carbonate fuel cell comprising the supported catalyst as a direct internal reforming catalyst.

Disclosed here is a supported catalyst comprising a thermally stable core, wherein the thermally stable core comprises a metal oxide support and nickel disposed in the metal oxide support, wherein the metal oxide support comprises at least one base metal oxide and at least one transition metal oxide or rare earth metal oxide mixed with or dispersed in the base metal oxide. Optionally the supported catalyst can further comprise an electrolyte removing layer coating the thermally stable core and/or an electrolyte repelling layer coating the electrolyte removing layer, wherein the electrolyte removing layer comprises at least one metal oxide, and wherein the electrolyte repelling layer comprises at least one of graphite, metal carbide and metal nitride. Also disclosed is a molten carbonate fuel cell comprising the supported catalyst as a direct internal reforming catalyst.

A fuel cell single unit including: a fuel cell element in which an anode layer and a cathode layer are formed so as to sandwich an electrolyte layer; a reducing gas supply path for supplying a gas containing hydrogen to the anode layer; an oxidizing gas supply path for supplying a gas containing oxygen to the cathode layer; and an internal reforming catalyst layer, which has a reforming catalyst for steam-reforming a fuel gas, in at least a part of the reducing gas supply path is provided. An external reformer, which has a reforming catalyst for steam-reforming the fuel gas, is provided upstream of the reducing gas supply path, and the fuel gas partially reformed by the external reformer is supplied to the reducing gas supply path.

A fuel cell single unit including: a fuel cell element in which an anode layer and a cathode layer are formed so as to sandwich an electrolyte layer; a reducing gas supply path for supplying a gas containing hydrogen to the anode layer; an oxidizing gas supply path for supplying a gas containing oxygen to the cathode layer; and an internal reforming catalyst layer, which has a reforming catalyst for steam-reforming a fuel gas, in at least a part of the reducing gas supply path is provided. An external reformer, which has a reforming catalyst for steam-reforming the fuel gas, is provided upstream of the reducing gas supply path, and the fuel gas partially reformed by the external reformer is supplied to the reducing gas supply path.

A method of operating a solid oxide cell system comprises generating an electrochemical conversion from one of: (i) water steam H.sub.2O(g); and (ii) a mixture comprising water steam H.sub.2O(g) and carbon dioxide CO.sub.2. A quantity of at least one other substance is added into the one of the water steam H.sub.2O(g) and the mixture comprising water steam H.sub.2O(g) and carbon dioxide CO.sub.2. The at least one other substance comprises a hydrocarbon C.sub.mH.sub.n. The quantity of the at least one other substance is converted into a syngas CO+H.sub.2. An endothermic reforming of the mixed-in hydrocarbons occurs by coupling-in waste heat from the electrochemical conversion. The additional quantity of the at least one substance is added compensate for effects of a degradation of the solid oxide cells of the solid oxide cell system. A total quantity of the hydrogen H.sub.2 generated by the solid oxide cell system is kept constant.

A method of operating a solid oxide cell system comprises generating an electrochemical conversion from one of: (i) water steam H.sub.2O(g); and (ii) a mixture comprising water steam H.sub.2O(g) and carbon dioxide CO.sub.2. A quantity of at least one other substance is added into the one of the water steam H.sub.2O(g) and the mixture comprising water steam H.sub.2O(g) and carbon dioxide CO.sub.2. The at least one other substance comprises a hydrocarbon C.sub.mH.sub.n. The quantity of the at least one other substance is converted into a syngas CO+H.sub.2. An endothermic reforming of the mixed-in hydrocarbons occurs by coupling-in waste heat from the electrochemical conversion. The additional quantity of the at least one substance is added compensate for effects of a degradation of the solid oxide cells of the solid oxide cell system. A total quantity of the hydrogen H.sub.2 generated by the solid oxide cell system is kept constant.

A fuel cell system comprising at least one fuel cell arranged for a reformation of a hydrocarbon and a hydrocarbon generation unit connected to an anode outlet of the fuel cell for generating the hydrocarbon from carbon monoxide and hydrogen included in a partially unconverted exhaust stream of the anode outlet of the fuel cell, where the fuel cell is thermally decoupled from the hydrocarbon generation unit so that the exothermal hydrocarbon generation reaction and the endothermal reformation reaction proceed without one reaction thermally interfering the other.

A fuel cell system comprising at least one fuel cell arranged for a reformation of a hydrocarbon and a hydrocarbon generation unit connected to an anode outlet of the fuel cell for generating the hydrocarbon from carbon monoxide and hydrogen included in a partially unconverted exhaust stream of the anode outlet of the fuel cell, where the fuel cell is thermally decoupled from the hydrocarbon generation unit so that the exothermal hydrocarbon generation reaction and the endothermal reformation reaction proceed without one reaction thermally interfering the other.